1. Field of the Invention
The present invention relates to a machine comprising a machine frame supported on undercarriages adapted to support the machine frame on a track comprised of rails fastened to ties defining cribs therebetween, and a ballast scarifying device for removing ballast from a respective one of the cribs between the rails.
2. Description of the Prior Art
U.S. Pat. No. 5,125,345 discloses a tie exchange machine in which a ballast scarifying device is arranged to remove ballast from a crib adjacent the tie to be exchanged. The ballast scarifying device is comprised of four ballast clearing plates spaced from each other in a direction extending transversely to the machine frame. Pairs of the ballast clearing plates may be independently displaced in a transverse direction towards a respective one of the track shoulders. This transverse displacement will remove the ballast from the crib towards the track shoulders.
French patent No. 2,588,023 and German patent No. 1,116,257 disclose machines with endless bucket chains for clearing ballast from a track bed. The bucket chain is lowered into the ballast between the track rails to excavate the ballast and convey it upwards to a conveyor band. Before the bucket chain is immersed in the ballast, the track ties must be removed.
U.S. Pat. No. 4,611,541 discloses a ballast cleaning machine in which an endless ballast excavating chain is mounted between two tie exchange devices to remove the entire ballast of the track bed and to convey it to a cleaning screen.
U.S. Pat. No. 5,513,452 also deals with an installation for the rehabilitation of a ballast bed. A first ballast excavating device is arranged at the front of the installation for receiving clean ballast deposited on the track, and this clean ballast is conveyed behind a second ballast excavating device which clears the dirty ballast to expose the subgrade. The dirty ballast is cleaned and returned to the exposed subgrade where the clean ballast conveyed from the first ballast excavating device is used to supplement the cleaned ballast.